Sciencemadness Discussion Board

Heavy Sulfuric Acid

subsecret - 28-2-2014 at 17:52

I recently purchased small bottle of drain opener (Master Jack brand, not well-known), and I was amazed by the mass of the bottle. I understand that sulfuric acid is more dense than water, but my other bottle contains acid that is much less dense.

Sulfuric acid drain openers often contain recycled acid from industrial processes, and I assume that this acid contains a large amount of metallic contaminants.

What could the metallic contaminants be?

ScienceHideout - 28-2-2014 at 18:33

You should test the purity gravimetrically. Take a 10 or 100 mL sample of acid and weigh it, as precise and accurate as possible. Does it meet the specific gravity of pure H2SO4 in the CRC handbook?

I guess it is possible that contaminates may cause extra weight, but I doubt that it would be that much noticeably heavier. I guess it is always worth checking!

By the way, aren't the majority of sulfates insoluble? Is there any solid in the bottom of the container?

thesmug - 28-2-2014 at 18:33

Quote: Originally posted by Awesomeness  
I recently purchased small bottle of drain opener (Master Jack brand, not well-known), and I was amazed by the mass of the bottle. I understand that sulfuric acid is more dense than water, but my other bottle contains acid that is much less dense.

Sulfuric acid drain openers often contain recycled acid from industrial processes, and I assume that this acid contains a large amount of metallic contaminants.

What could the metallic contaminants be?

Judging from what kinds of processes sulfur comes from, steel and aluminum come to mind. With steel there is obviously also going to be iron. It might also contain some of the heavier metals like lead. I know what this isn't what you were asking but it might also contain petroleum byproducts.

cyanureeves - 28-2-2014 at 18:45

about metal sulfates,i also thought that the sulfates would precipitate and leave rather pure sulfuric acid. rooto sulfuric acid is also pretty heavy and almost feels like it is being pulled down with magnetic force.

Emphasis on heavy

Gearhead_Shem_Tov - 28-2-2014 at 18:48

Did anyone else but me read the original subject line and think, "Huh, I wonder what the chemical properties of D2SO4 would be; are they any different to H2SO4?"

-Bobby

Zyklon-A - 28-2-2014 at 19:00

It should be noted that just because most sulfates are insoluble in water, doesn't mean that they are insoluble in con. sulfuric acid. BaSO4 is soluble in sulfuric acid.
[EDIT]
Quote:

Did anyone else but me read the original subject line and think, "Huh, I wonder what the chemical properties of D2SO4 would be; are they any different to H2SO4?"
-Bobby

"Chemical properties"? Not so much, physical properties? Yes.
BTW, You can buy deuterium sulfuric acid.

[Edited on 1-3-2014 by Zyklonb]

subsecret - 28-2-2014 at 19:07

Thanks for the quick responses :)

There is no solid material collected on the bottom, and I don't think that this acid is terribly concentrated. Its reaction with sucrose is considerably slower than that of Rooto sulfuric acid. I'd to a titration, but I lack phenolpthalein.

I suppose it's too far a stretch to think that this acid is recycled from batteries. The EPA would never allow that!

[Edited on 1-3-2014 by Awesomeness]

plante1999 - 28-2-2014 at 19:22

Batteries are generally burned and melted, and the gases converted to the recycled acid.

thesmug - 28-2-2014 at 19:49

Quote: Originally posted by Gearhead_Shem_Tov  
Did anyone else but me read the original subject line and think, "Huh, I wonder what the chemical properties of D2SO4 would be; are they any different to H2SO4?"

-Bobby

I did :D

ScienceHideout - 1-3-2014 at 07:42

Quote: Originally posted by Awesomeness  
I'd to a titration, but I lack phenolpthalein.
[Edited on 1-3-2014 by Awesomeness]


You don't necessarily need phenolphthalein to do a titration... because the "slope" near the equivalence point is so steep, any indicator that changes color between 6 and 8 should work... universal indicator, litmus, BTB, heck, even red cabbage! :D

vmelkon - 1-3-2014 at 07:44

Quote: Originally posted by plante1999  
Batteries are generally burned and melted, and the gases converted to the recycled acid.


It depends on the method

https://www.youtube.com/watch?v=aH_HKeS1Ed4
IN That method, they crush the battery
float the plastic, remove and send the plastic to another company that turns it into pellets and then back to car battery shape.
The acid is neutralised (not sure how) and dumped into the river.
The lead is melted and turned into bars.

I don't know what they do with the PbO2, PbSO4, and some of the minor stuff like BaSO4.

turd - 1-3-2014 at 09:44

Quote: Originally posted by Zyklonb  
"Chemical properties"? Not so much, physical properties? Yes.

The kinetic isotope effect (https://en.wikipedia.org/wiki/Kinetic_isotope_effect) of the H/D pair can be surprisingly large.

Zyklon-A - 2-3-2014 at 13:07

True, that is the reason that D2O is assumed to be slightly toxic. https://www.youtube.com/watch?v=fyK6kPi8k78

subsecret - 30-3-2014 at 17:46

UPDATE

I finally got around to it, and I calculated the density of the Rooto sulfuric acid, but not the unusually heavy sulfuric acid. As it turns out, the Rooto stuff had a density of 1.8356 g/mL (disregarding significant figures), while the recorded density of pure sulfuric acid is 1.84 g/mL. 25 mL of Rooto sulfuric acid weighed 45.89 g. Rooto is surprisingly pure... or perhaps the weight of the metallic contaminants is balanced by the water content.

BromicAcid - 30-3-2014 at 18:55

Do not rely on the reaction of the acid with sucrose, metals, etc to determine purity. It is my understanding that many of those brands contain a brew of inhibitors that are added that can cause all sorts of funky reactivity. I had some drain opener at one time that didn't want to have anything to do with zinc metal in any concentration. After distillation it attacked it nicely.